In an era of scarce resources and increasing population, it is desirable to reclaim and reuse as many resources as possible. In the textile industry, for many years wool clothing and other types of woolen products have been torn apart using a process known as garnetting and the fibers reused in clothing and wool rugs. Garnetting is a process by which material such as threads, rags, woven cloth scraps, and the like are broken up and returned to a substantial fluffy, fibrous condition simulating the original condition of the fiber. This is done by first chopping the material to small pieces (e.g. two to six inches) and then running the pieces through a series of high speed cylinders which can be covered with wire (e.g. saw wire), steel spikes, or the like. The treatment breaks up the material into individual fibers typically having a length of one and one-eighth inches or less.
Despite the known desirability of reusing resources, and the known recycling of woolen products for many years, attempts to reclaim and reuse cotton fibers from old garments, scraps and rags have encountered large obstacles which have always prevented the development of a practical, commercial approach. Garnetting or separation of the cotton fiber from the original materials must be severe enough to cause fiber separation, but in so processing the materials, the fibers produced were damaged and broken. The result was very short fibers, typically of one-half inch or less, which are too short to make into yarn and fabric using commercial processes. Therefore the recycling or reclamation of cotton fibers has typically been restricted to the production of low end textile products, such as mops or non-woven materials.
According to the present invention, a method and fabric are provided whereby denim cotton fibers can effectively be reclaimed. The fabric produced according to the invention has properties comparable to that of denim fabric made from virgin yarn, and is suitable for essentially all apparel applications that virgin denim yarn may be used for. While the invention is also useful in association with post-consumer denim waste material, it is particularly useful to employ pre-consumer denim waste such as cutting table scraps of denim cotton fabrics, actual cotton thread, denim yarn waste, and denim fabric scraps left over from the cutting out of patterns for garments. This has an enormous potential for resource recovery due to the large volume of denim garments that are produced yearly, from indigo dyed denim and sulfur black dyed denim and other colors using millions of pounds of cotton each year. For example, the consumption of cotton for denim fabric in the United States during 1992 was over 800 million pounds. Cloth scraps make up approximately 10% of this amount, depending upon patterns cut, meaning that there is presently annual waste to landfills or incinerators for denim scraps alone of close to 80 million pounds per year since the markets for the low end textile products using cotton fibers typically do not employ denim, or if they do only a small fraction of the denim waste that exists is employed.
According to the invention, denim yarns and denim fabrics can be produced containing from about 40% to 100% (preferably about 60-100%) of reclaimed cotton from pre-consumer denim waste and/or post-consumer denim waste. According to the present invention it has been found that if the appropriate treatment steps are practiced and if the garnetted scrap material is carded in a low tension manner, it is possible to spin yarn from the reclaimed denim waste fibers, and produce yarns for weaving or knitting, e.g. filling yarn having a yarn count of about 4.0/1 to 12.0/1, and warp yarn (for plying with itself or with virgin yarn) having a yarn count of about 9.0/1 to 16.0/1.
According to one aspect of the present invention a method of making denim fabric is provided comprising the steps of substantially sequentially: (a) Collecting denim waste. (b) Garnetting the denim waste to produce denim fibers with the vast majority having fiber lengths greater than about 0.4 inches (and the average fiber length greater than about 0.5 inches). (c) Opening the denim fibers. (d) Low-tension carding the opened denim fibers. (e) Spinning the carded denim fibers into yarn. And, (f) weaving or knitting the yarn into fabric having at least about 40% of the total fiber content of the fabric from the denim waste collected in step (a).
There may also be the further steps of adding lubricant to the fibers after step (b), for example, between steps (b) and (c); removing size and starch from the denim waste prior to step (b); sorting the denim waste by color between steps (a) and (b) and separately processing different colors of denim waste, making the denim fabric into denim apparel; and after either step (e) or step (f) dyeing the yarn or fabric to produce a substantially uniform color of fabric. There may also be the further step, between the opening and carding steps, of cleaning the fibers, as with an ERM feeder. There also may be the further step of adding some virgin denim fiber, up to about 50% (preferably up to about 40%) of the total fiber content, to the denim fibers from step (b) prior to step (d).
Where step (f) is weaving, step (e) is practiced to produce filling yarns; step (e) is also typically practiced to produce yarn and step (f) is practiced using both filling and warp or knitting yarn from step (e). There is also the option of a further step of plying the warp yarns from step (e) together before practicing step (f), or plying warp yarns from step (e) together with virgin denim yarn before practicing step (f).
The size removal step--if utilized--is typically practiced by treating the denim material with amylase enzyme. Step (a) may be practiced by collecting pre-consumer denim waste only, or by collecting post-consumer denim waste, or both pre-consumer and post-consumer denim waste. For the post consumer denim waste there is preferably the further step of removing non-denim materials (for example, zippers, buttons, rivets, leather patches and the like) from the waste prior to other processing. Also steps (e) and (f) may be practiced to produce denim fabric having approximately 100% of the fiber content thereof from the fiber collected in step (a), and step (e) may be practiced using a Rieter C-4 type card (or a Rieter C-5 or C-10) with a conveyor belt.
According to another aspect of the present invention a woven denim fabric having warp and filling yarns is provided by practicing the steps of the method set forth above. Step (f) may also be practiced to make the warp yarn, where the filling yarn of the fabric has a yarn count of about 4.0/1 to 12.0/1, and the warp yarn is warp yarn from step (f) having a yarn count of about 4.0/1 to 16.0/1 and could be plied with other warp yarn from step (f), or with virgin denim yarn.
One aspect of the present invention is a knitted fabric made from yarns produced in step (f).
According to another aspect of the present invention a woven denim fabric is provided having filling and warp yarns. The fabric has substantially 100% of the filling yarn made from pre-consumer, post-consumer, or both pre-consumer and post-consumer denim waste, and has at least about 40% of the total of filling and warp yarns made from pre-consumer, post-consumer, or both pre-consumer and post-consumer denim waste. The fabric may have about 100% of the total of filling and warp yarns made from pre-consumer, post-consumer, or both pre-consumer and post-consumer denim waste.
The invention also contemplates a knit fabric from denim waste made by practicing the steps of substantially sequentially: (a) collecting denim waste; (b) garnetting the denim waste to produce denim fibers having the vast majority of the fiber lengths greater than about 0.4 inches; (c) opening the denim fibers; (d) low-tension carding the opened denim fibers; (e) spinning the carded denim fibers into yarn; and (f) knitting the yarn into fabric having at least about 40% of the total fiber content of the fabric from the denim waste collected in step (a).
It is the primary object of the present invention to make apparel-quality denim fabric (and apparel therefrom) from denim waste. This and other objects of the invention will become clear from an inspection of the detailed description of the invention and from the appended claims.